This invention relates in general to pallet loading and unloading equipment and in particular to apparatus for raising pallets to a convenient height for the loading and unloading of goods by operators.
It is customary in moving and warehousing operations to utilize wooden pallets on which goods are stacked in tiers. The loaded pallets may then be moved from place to place by means of hand pallet trucks or forklifts. The pallets take the form of platforms having two separated horizontal surfaces with an open area between the two surfaces in which the forklift or pallet jack may be inserted. In use, the top surface of the pallet is conventionally about 6" above the floor level and the first tier or layer of goods stacked on the pallet requires that the worker bend from the waist or stoop to load or unload the goods in that tier. The repeated bending or stooping accompanied by lifting of materials, particularly heavy materials, inevitably results in worker fatigue, strain, and, frequently, injury. Another common problem involved in palletized shipping or warehousing is the tendency of some materials when stacked to slide off the pallet or off lower tiers on which they are placed. Some restraint such as an enclosing wall about the pallet to retain goods in place in the tiers would avoid such slippage.
The problems outlined have been avoided to some extent by automating the processes and in some cases by resorting to robot loading machines or apparatus. Such expedients are inordinately expensive, however, and are usually highly specialized in that each job must be individually and specifically addressed to provide a customized solution.
There has been also been developed a pallet-loading device which utilizes a cradle vertically movable in an enclosure and having a scissors-jack lifting mechanism in each opposing side of the three-sided enclosure. This device has achieved some acceptance, but has been found objectionable because of the width of the side walls necessitated by the inclusion therein of the scissors-jack type lifting mechanism. Wide side walls are inconvenient and somewhat hazardous to operators who must reach and stretch to reach over such walls to handle goods. Moreover, the two scissors-type jacks utilized must be in synchronized operation for smooth lifting of the pallet and goods. Where hydraulic power is used, some provision must be made to equalize the flow of hydraulic fluid. Generally, a flow divider or similar accessory is required in the hydraulic circuit which adds to the complexity and cost of the equipment.
A primary object of the present invention is the provision of a simple universally applicable device for positioning pallets at a convenient height for loading and unloading by a worker.
Another object of the present invention is to provide an open-topped three-sided enclosure in which tiers of goods stacked on a pallet may be prevented from spilling or sliding from the pallet or from the lower tiers of material,
A further object of the present invention is the provision of a pallet lift apparatus in which the working height is adjustable by the use of conveniently located controls.
A still further object of the present invention is a pallet-loading apparatus which is easily movable from place to place by means of a hand pallet truck or forklift.
Yet another object of the present invention is a pallet lift apparatus in which the lift platform is a cantilever support structure, the operating mechanism for which is housed in an end wall, the side walls of the housing being conveniently narrow to minimize equipment size to protect workers from hazards.